1. Field of the Invention
The present invention relates to a refrigerator, and more particularly to an air curtain fan driving device and a method for driving an air curtain fan according to interior and exterior conditions during a defrosting operation of a refrigerator.
2. Description of the Prior Art
Generally, the normal operation of the refrigerator is carried out while the mode is appropriately changed into a cooling mode for cooling the interior of the refrigerator or a defrosting mode for defrosting frost formed on the cooler.
Viewing the refrigerant circulation cycle in a refrigerator, as a gas refrigerant with high-temperature and high-pressure created by a compressor passing through a condenser, the gas refrigerant transmits its heat to the exterior and is converted into liquid refrigerant. Thereafter, the liquid refrigerant, which still has high pressure, passes through a dryer, so that foreign materials and the water component in the liquid refrigerant are removed, and the liquid refrigerant without the foreign materials and water moves to the capillary tube. The liquid refrigerant moving through the capillary tube expands in a liquid/gas-mixed state to easily evaporate, thereby absorbing ambient heat in order for the refrigerant to return to the original refrigerant condition. Accordingly, the refrigerant is repeatedly circulated as a cooling air supply in the refrigerator.
Meanwhile, during the cooling operation of the refrigerator, frost is formed on the cooler since the temperature in the refrigerator changes by opening the door of the refrigerator. The amount of frost is determined by the operating time of the compressor, external temperature, the frequency in door opening of the refrigerator, external humidity, and the time the door remains open. Frost formed on the cooler causes a decrease in cooling efficiency.
Accordingly, a microprocessor of the refrigerator changes the mode into the defrosting mode when more frost than the predetermined amount is formed. The defrosting mode comprises a pre-cooling step, a heating step, a compressor pausing step, and a cooling fan pausing step. The pre-cooling step is for lowering the temperatures of the refrigerating compartment and the freezing compartment of the refrigerator before driving the heater. The heating step is to carry out the defrosting operation. The compressor pausing step is for pausing the compressor drive to prevent it from overheating. The cooling fan pausing step is for pausing the cooling fan drive until the cooler is cooled under the predetermined temperature.
During operation of the refrigerator, the interior temperature of the refrigerator may rise due to an overload in the refrigerating compartment of the refrigerator and if the exterior air flows in the refrigerating compartment while the refrigerating compartment door is opened. At this time, in order to restore the interior temperature of the refrigerating compartment to its normal state, an air curtain fan has been mounted in the refrigerating compartment in recent years.
A temperature control method for refrigerator is disclosed, in U.S. Pat. No. 5,263,332 granted to Mr. Park on Nov. 23, 1993, for reducing the cooling time by stabilizing the temperature fluctuation occurring when the refrigerator door is opened. The patent includes a step for controlling a compressor and a fan for a normal operation in order to maintain interior temperature of a refrigerator at a temperature preset by a user (called "normal operation step"). In a door-opening control step, if opening of a door of the refrigerator is detected, the fan is turned off, and a time period during the opening of a door of the refrigerator is calculated until closing of the door is detected. Thereafter, if the closing of the door is detected, a temperature-resetting step restarts the normal operation step after automatically resetting the preset temperature based on the calculated time period. A reset temperature operation step determines whether the temperature is reset during the normal operation step. If the temperature is reset, the compressor and the fan are driven for a cooling operation until the temperature reaches reset temperature. Thereafter, the reset temperature operation step restarts the normal operation step. The patent of Mr. Park enhances food preservation and the efficiency of the refrigerator since the interior temperature influenced by exterior air when a door of the refrigerator has been opened is rapidly stabilized after the closing of the door.
Hereinafter, a conventional air curtain fan driving device will be described in detail with reference to FIG. 1. FIG. 1 is a view for showing a conventional air curtain fan driving device. The conventional air curtain fan driving device 10 includes an air curtain fan 100, a temperature detector 102, a compressor 104, a compressor driver 106, a cooling fan 108, a cooling fan driver 110, an air curtain fan driver 112, and a controller 114.
The temperature detector 102 detects an interior temperature T1 of the refrigerator under the control of the controller 114. The detection of the interior temperature T1 of the refrigerator is applied to the controller 114. The compressor 104 converts normal gas refrigerant into gas refrigerant of high temperature and high pressure. The compressor driver 106 controls the driving of the compressor 104. The cooling fan 108 blows cool air into the refrigerating compartment. The cooling air is provided from the evaporator (not shown). The cooling fan driver 110 controls the driving of the cooling fan 108. The controller 114 controls the operations of the temperature 102, compressor driver 106, cooling fan driver 110, and air curtain fan driver 112. The controller 114 causes normal cooling operations to be performed since the controller 114 drives the compressor 104 and cooling fan 108 by the compressor driver 106 and cooling fan driver 110 respectively. The controller 114 determines whether the interior temperature T1 of the refrigerating compartment detected by the temperature detector 102 is normal.
Hereinafter, operations of the conventional air curtain fan driving device will be described in detail.
FIG. 2 is a flow chart for explaining operations of the conventional air curtain fan driving device of FIG. 1.
When electric power is applied, the controller 114 drives the compressor 104 and cooling fan 108 by means of the compressor driver 106 and cooling fan driver 110 respectively, so that normal cooling operations are performed (step S201). The temperature detector 102 detects an interior temperature T1 of the refrigerator under the control of the controller 114 (step S202). The detected interior temperature T1 is transmitted to the controller 114. The controller 114 determines whether the detected interior temperature T1 is a normal temperature by the temperature detector 102 (step S203). If the detected interior temperature T1 is below or over the normal temperature as a result of the determination of the step S203, the compressor driver 106 drives the compressor 104 under the control of the controller 114 (step S204). Thereafter, the cooling fan driver 108 and the air curtain fan driver 112 drive the cooling fan 108 and the air curtain fan 100 under the control of the controller 114 respectively (step S205). In step 206, the controller 114 determines again whether the detected interior temperature T1 by the temperature detector 102 is the normal temperature. If the detected interior temperature T1 is below or over the normal temperature as a result of the determination of the step S206, the step S204 is restarted.
In the meantime, if the detected interior temperature T1 is determined as the normal temperature, the controller 114 enables the normal cooling operations to be performed (S207).
With the conventional method mentioned above, the air curtain fan is driven when the door of the refrigerator is opened regardless of the interior condition of the refrigerator, i.e., regardless of whether the operating mode is the cooling one or the defrosting one.
The air curtain fan is driven even in the defrosting mode when the door of the refrigerator is opened. That is to say, in the heating step of the defrosting mode, the temperature of the cooler can be higher than the required temperature in the normal cooling operation. If the air curtain fan is operated in this case, then air of a higher temperature passing through the cooler flows into the refrigerating compartment and the freezing compartment, which causes a decrease in cooling efficiency.